Syringe Needle Sheath

ABSTRACT

A syringe is provided which comprises a barrel ( 11 ) and a needle sheath ( 30 ) slidably located within the barrel, a plunger ( 20 ) with a plunger seal ( 23 ), a needle, a needle sheath ( 30 ) and a sheath seal ( 50 ), arranged so that depression of the plunger forces the needle sheath to move into a position where it covers or at least partly encloses the needle after delivery of fluid contents of the syringe. The needle sheath may be manually actuated or may be actuated by decompression of a spring. The syringe may further comprise a plunger disabling means operable to impede, prevent or otherwise hinder withdrawal of the plunger during or following depression of the plunger. The syringe may be a pre-filled syringe or a syringe which is filled by a user.

FIELD OF THE INVENTION

THIS INVENTION relates to syringes. More particularly, this inventionrelates to a syringe that comprises a sheath mechanism to prevent orminimize the risk of needlestick injury. This invention also relates toa syringe that comprises a sheath mechanism to prevent or minimize therisk of needlestick injury and a plunger disabling means to impede,prevent or otherwise hinder withdrawal of the plunger during orfollowing depression of the plunger.

BACKGROUND OF THE INVENTION

The practice of sharing syringes without adequate sterilisation betweensuccessive users is a major contributor to the transfer of HumanImmunodeficiency Virus (HIV) and Hepatitis with subsequent severerepercussions for the sufferer and at a high cost to society forsupporting and providing medical attention to sufferers.

In response to this problem, syringes have been developed with the aimof preventing syringe re-use.

A particular problem associated with syringes is needlestick injury tothe user.

One solution has been to develop syringes where the needle ispermanently retractable into the barrel of the syringe, retractiondriven by a compressed spring, as for example described in InternationalPublication WO 01/80930.

Although very effective, retractable syringes are relatively expensive,particularly when required in large quantities for mass immunizations orfor distribution to intravenous drug users. This is particularly aproblem in third world countries where the incidence of HIV is high,mass immunization programs need to be frequently undertaken andhealthcare resources are limited.

There is therefore a need to produce a syringe that automaticallyprevents or minimize the risk of syringe re-use and/or needlestickinjury and that is relatively inexpensive to produce.

With this need in mind, syringes with non-retractable needles have beendeveloped, wherein a cover or sheath is activated to cover the needleafter syringe use.

In this regard, reference is made to U.S. Pat. No. 6,086,566 and U.S.Pat. No. 6,428,519 which describe a movable needle cover A particularfeature of these prior art syringes is that they are relativelycomplicated, each requiring a guiding member to assist guided movementof the cover over the needle and also to positively retain the movablecover in its protection position over the needle.

Reference is also made to U.S. Pat. No. 6,565,540 which describes aspring actuated, movable needle cover. A disadvantage of this syringeneedle cover is that the spring is gradually compressed during plungerdepression, which provides an unacceptable “feel” to the syringe userand hence detracts from the commercial attractiveness of the syringe.

SUMMARY OF THE INVENTION

The present invention is therefore broadly directed to syringe needlesheath operable to prevent or minimize the risk of needlestick injuryand/or syringe re-use and which overcomes one or more disadvantages ofthe prior art or at least provides a commercially suitable alternative.

In one broad form, the invention provides a manually-actuated needlesheath.

In another broad form, the invention provides a spring-actuated needlesheath.

In yet another broad form, the invention provides a syringe comprising aneedle sheath and a plunger disabling means.

In a first aspect, the invention provides a needle sheath for a syringehaving a barrel, plunger and a needle, said needle sheath slidablylocated within the barrel and said operable to cover or at least partlyenclose the needle after delivery of fluid contents of the syringe.

In a second aspect, the invention provides a syringe comprising a barreland a needle sheath slidably located within the barrel, a plunger and aneedle, said needle sheath operable to cover or at least partly enclosethe needle after delivery of fluid contents of the syringe.

In one particular embodiment, the syringe comprises a barrel, a needlemounted to the barrel, a plunger, a needle sheath and a sheath seal,arranged so that depression of said plunger urges or forces said sheathseal to bear against said needle sheath and thereby move said needlesheath to cover or at least partly enclose the needle after delivery offluid contents of the syringe.

In another particular embodiment, the needle sheath mechanism isspring-activated.

In a preferred form of this embodiment, the syringe comprises a barrel,a needle mounted to a needle mount that is fitted to the barrel, aplunger, a needle sheath, an initially compressed spring and a sheathseal, arranged so that depression of said plunger urges or forces saidsheath seal to bear against said needle sheath and thereby release saidneedle sheath from said needle mount and thereby facilitatedecompression of said spring to move said needle sheath so as to coveror at least partly enclose the needle after delivery of fluid contentsof the syringe.

The syringe may be a prefilled syringe or a syringe that is fillable byplunger withdrawal.

In a particularly preferred form, the syringe further comprises aplunger disabling means.

Suitably, the plunger disabling means is operable to impede, prevent orotherwise hinder withdrawal of the plunger during or followingdepression of the plunger.

In one particular embodiment, the plunger disabling means comprises oneor more clips, ledges, tabs or the like located at a plunger end of saidbarrel and which are capable of engaging said plunger to thereby impede,prevent or otherwise hinder withdrawal of said plunger during orfollowing depression of said plunger.

In another particular embodiment, the plunger disabling means isessentially as described in International Application PCT/AU2005/000106,which is herein incorporated by reference in its entirety.

In one form of this particular embodiment, the plunger comprises twoopposed ratchets disposed along the plunger rod, which ratchets arerespectively alignable with two pawls so as to be capable of engagementby the pawls and thereby impede, prevent or otherwise hinder withdrawalof the plunger during or following depression of the plunger. Thesyringe further comprises a collar at a plunger end of the barrel, thecollar having an inner member and an outer member that are incapable ofrotation relative to each other. The outer member comprises said twopawls and further comprises two fingers that respectively slidablyengage opposed guide slots on the plunger to thereby prevent or minimizerotation of the plunger relative to the collar. The inner member of thecollar is operable to prevent engagement of the plunger ratchet by thetwo pawls until the plunger is depressed.

Throughout this specification, unless otherwise indicated, “comprise”,“comprises” and “comprising” are used inclusively rather thanexclusively, so that a stated integer or group of integers may includeone or more other non-stated integers or groups of integers.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the invention are described herein withreference to drawings wherein:

FIG. 1 is a side sectional view of a syringe having a needle sheath;

FIG. 2 is a side sectional view of a plunger;

FIG. 3A is a side sectional view of a needle mount, needle sheath andsheath seal fitted into a syringe barrel and FIG. 3B is a perspectiveview of a needle mount;

FIG. 4 is a side sectional view of a plunger, plunger seal, needlemount, needle sheath and sheath seal towards the end of plungerdepression;

FIG. 5 is a side sectional view at the end of plunger depression whereina needle sheath covers a cannula;

FIG. 6 shows a perspective view of components of another embodiment of asyringe having a needle sheath;

FIGS. 7A, 7B and 7C are respective sectional views of an embodiment of aprefilled syringe having a needle sheath showing the prefilled syringebefore delivery (A), at the end of delivery (B) and after deployment ofneedle sheath (C);

FIG. 8 is a side sectional view of a syringe having a spring-activatedneedle sheath;

FIG. 9 is a side sectional view of a plunger;

FIG. 10 is a side sectional view of a needle mount, needle sheath withspring and sheath seal fitted into a syringe barrel;

FIG. 11 is a perspective view of a needle mount and needle sheath;

FIG. 12 is a side sectional view at the end of plunger depressionwherein a spring-activated needle sheath covers a cannula;

FIG. 13 is a side sectional view of an alternative embodiment of asheath seal; and

FIG. 14A is a side sectional view of syringe comprising a plungerdisabling means before plunger depression and

FIG. 14B is a side sectional view of syringe comprising a plungerdisabling means after plunger depression.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, syringe 10 comprises barrel 11, plunger 20, needlesheath 30, needle mount 40 and sheath seal 50. Barrel 11 comprisesneedle end 13 in which is located needle mount 40 comprising cannula 41.Protective cap 90 covers cannula 41 and is removed prior to use ofsyringe 10. Barrel 11 also comprises plunger end 14 at which are locatedpaired finger grips 15A, 15B. Plunger seal 23, sheath seal 50 and insidewall 18 of barrel 11 define fluid space 60 inside barrel 11.

Referring to FIG. 1 and FIG. 2, plunger 20 comprises plunger rod 21 andbutton 22 operable by a user to facilitate plunger 20 depression.Plunger 20 further comprises plunger seal 23 having ribbed sealingmember 27, which is coupled to plunger rod 21 by way of coupling member24 on plunger rod 21 engaging complementary recess 25 in plunger seal23. Coupling member 24 comprises bore 26 to receive cannula 41 ashereinafter described.

In this particular embodiment, coupling member 24 and complementaryrecess 25 are screw-threadedly engaged.

Referring to FIG. 1 and FIGS. 3A and 3B needle sheath 30 comprisessheath body 31 having paired legs 32A, 32B that define groove 34 andcannula bore 35. Legs 32A, 32B respectively comprise stepped or barbedends 33A, 33B.

Needle mount 40 is fitted at needle end 13 of barrel 11 through base 43of needle mount body 42 being locatable within inner groove 17 of barrel11. As best seen in FIG. 3B, needle mount body 42 further comprises cap44 that comprises aperture 47, web 45 that supports boss 46 which inturn supports cannula 41, recess 48 and shoulder 49.

Needle sheath 30 is mounted into needle mount 40 so that legs 32A, 32Bare located either side of web 45.

Sheath body 31 fits into aperture 47 to thereby co-operate with needlemount 40 to close needle end 13 of barrel 11. Notches 37A, 37B on sheathbody 31 locate in recess 48 inside needle mount body 42 to hold needlesheath 30 in place. Sheath seal 50 is mounted inside barrel 11 andengages step 19, which prevents sheath seal 50 being retracted whenplunger 20 is withdrawn to fill syringe 10. Sealing body 51 of sheathseal 50 abuts respective stepped ends 33A, 33B of legs 32A, 32B ofsheath body 31 while boss 52 supports end 400 of cannula 41. Sealingmember 58 of sheath seal 50 forms a fluid-tight tight seal with insidewall 18 of barrel 11.

Depression of plunger 20 expels fluid from fluid space through cannula41.

Referring to FIG. 4, towards the end of plunger 20 injection stroke,plunger seal 23 moves through fluid space 60, as indicated by the solidarrow, to eventually bear against sheath seal 50. As this occurs,cannula end 400 pierces plunger seal 23 and enters bore 26 in couplingmember 24 of plunger 20 to thereby prevent any movement of cannula 41.Continued depression of plunger 20 and plunger seal 23 coupled theretopushes sheath seal 50 against needle sheath 30 to move needle sheathfurther in the direction of needle end 13 of barrel 11 as indicated bythe solid arrow.

When needle sheath 30 reaches shoulder 49 on the inside of needle mountbody 42, cannula 41 is fully encapsulated by needle sheath 30, as shownin FIG. 5. Movement of needle sheath 30 will cease when stepped ends33A, 33B of legs 32A, 32B clips into recess 48 in body 42 of needlemount 40.

Referring now to an alternative embodiment shown in FIG. 6 and FIG.7A-C, syringe 110 comprises barrel 111 having finger grips 115A, 115B,plunger 120 having rod 121 and button 122, needle sheath 130, needlemount 140 and sheath seal 150. Note that in this embodiment, needlemount 140 is integral with needle end 113 of barrel 111, in contrast tothe separate structure described in FIGS. 1-6.

Cannula 141 is located at needle end 113 of barrel 111, mounted vianeedle mount 140. Needle mount 140 further comprises aperture 147, web145 that supports boss 146 which in turn supports cannula 141 and alsocomprises tabs 149A, 149B, 149C, 149D.

Needle sheath 130 is mounted into barrel 111 by way of ring 139 ofsheath body 131 bearing against tabs 149A, B, C, D in inner wall ofbarrel 111. Sheath seal 150 comprises sealing body 151, support boss 152and internal rim 153.

Sheath seal 150 is fitted to needle sheath 130 by way of barbed ends133A, 133B of respective legs 132A, 132B engaging internal rim 153 ofsheath seal 150. This prevents sheath seal 150 being drawn towardplunger end of barrel 111 during withdrawal of plunger 120 and fillingof barrel 111.

Initially, plunger seal 123, sheath seal 150 and inner wall 118 ofbarrel 211 define fluid space 160.

Depression of plunger 120 expels fluid from fluid space 160 throughcannula 141.

During plunger 120 depression, force applied to plunger 120 forcesplunger seal 123 against sheath seal 150 which is coupled to needlesheath 130. Tabs 149A, B, C, D are shaped so that after a certain amountof force is applied by plunger 120 on sheath seal 150 at the end ofinjection, needle sheath 130 will release therefrom in needle end 113 ofbarrel 111 so that sheath seal 150 and needle sheath 130 will continuemoving inside barrel 111 to thereby cover cannula 141. Groove 134 ofneedle sheath 130 surrounds web 145 and thereby allows needle sheath 130to move relative thereto. Sheath seal 150 slides down cannula 141,support boss 152 allowing cannula 141 to pass therethrough, as it pushesneedle sheath 130 down to cover cannula 141. Cannula 141 pierces plungerseal 123 and moves into bore 126 in plunger 120.

Movement of needle sheath 130 will cease when ledges 136A, 136B of legs132A, 132B of needle sheath 130 bear against web 145 of needle mount140.

Boss 146 provides lengthened support for cannula 141 and also allows fora larger cannula aperture 135 in needle sheath 130 to allow for easierassembly. Support boss 152 in sheath seal 150 accommodates and sealsaround end 400 of cannula 141 and sheath seal 150 seals needle end ofbarrel 111.

Reference is now made to FIGS. 8-13 which describe an embodiment of aspring-activated needle sheath.

Referring initially to FIG. 8, syringe 210 comprises barrel 211, plunger220, needle sheath 230, needle mount 240, sheath seal 250 and spring270. Barrel 211 comprises needle end 213 with sheath aperture 216through which protrudes part of needle sheath 230 and cannula 241mounted to needle mount 240. Sheath aperture 216 at needle end 213 ofbarrel 211 is bounded by rim 212. Barrel 211 also comprisescircumferential step 219 and circumferential ledge 217 on inner wall218. At plunger end 214 of barrel 211 are located paired finger grips215A, 215B. Plunger seal 223, sheath seal 250 and inner wall 218 ofbarrel 211 define fluid space 260. Sealing member 258 of sheath seal 250forms a fluid-tight tight seal with inside wall 218 of barrel 211.

Referring to FIG. 8 and FIG. 9, plunger 220 comprises plunger rod 221and button 222 operable by a user to facilitate plunger 220 depression.Plunger 220 further comprises plunger seal 223 having ribbed sealingmember 227, which is coupled to plunger rod 221 by way of screw couplingmember 224 on plunger rod 221 engaging complementary, threaded recess225 in plunger seal 223.

Referring to FIG. 10 and FIG. 11, needle sheath 230 comprises sheathbody 231 having cannula bore 235, ledge 234 and legs 232A, 232B, 232C,232D. Legs 232C, 232D are relatively splayed compared to legs 232A, 232Bwhich respectively terminate in stepped ends 233A, 233B.

Needle mount 240 is a separate structure as in FIGS. 1-6 and comprisesbody 242 having base 243 and cutaways 244A, 244B and web 245 thatsupports elongate boss 246 which in turn supports cannula 241.

Needle mount 240 is fitted at needle end 213 of barrel 211 either byadhesive or an interference fit between base 243 and circumferentialstep 219 on inside wall 218 of barrel 211, which prevents needle mount240 travelling further toward needle end 213 of barrel 211. Spring 270is fitted over cannula 241 and needle sheath 230 is placed over cannula241 and forced towards needle mount 240, thereby compressing spring 270.Needle sheath 230 is mounted into needle mount 240 so that legs 232A,232B are located either side of web 245 and elongate boss 246, steppedends 233A, 233B clipping under base 243 of needle mount body 242.

Splayed legs 232C, 232D are angularly disposed through cutaways 244A,244B and terminate against base 243 of needle mount body 242.

End 400 of cannula 241 extends through cannula bore 235 of needle sheath230 and elongate boss 246 to communicate with fluid space 260 in barrel211.

Sheath seal 250 comprises sealing body 251, aperture 255 and seat 256,which in this embodiment has a recessed taper. Sheath seal 250 iscoupled to needle mount 240 by way of elongate boss 246 fitting intoaperture 255. Cannula 241 extends through cannula bore 235 of needlesheath 230 and elongate boss 246 of needle mount 240 to communicate withfluid space 260 in barrel 211, although without extending beyond centralaperture 255 of sheath seal 250.

Initially, plunger seal 223 and sheath seal 250 define fluid space 260inside barrel 211.

Depression of plunger 220 expels fluid from fluid space 260 throughcannula 241.

Towards the end of plunger 220 injection stroke to deliver fluidcontents of syringe 210, plunger seal 223 engages sheath seal 250thereby moving sheath seal 250 in the direction indicated by the solidarrow shown in FIG. 10. Seat 256 of sheath seal 250 engages respectivestepped ends 233A, 233B of legs 232A, 232B of needle sheath 230, forcingthem radially inwards, thereby releasing needle sheath 230 which washeld in place under spring 270 bias.

Decompression of spring 270 drives needle sheath 230 in the direction ofneedle end 213 of barrel 211 as indicated by the solid arrow, so thatcannula 241 is fully encapsulated by needle sheath 230, as shown in FIG.12. Sheath 230 cannot travel beyond needle end 213 of barrel 211 or beremoved from barrel 211 because ledge 234 bears against rim 212 thatbounds sheath aperture 216.

When needle sheath 230 encapsulates cannula 241, splayed legs 232C, 232Dof needle sheath 230 clip out over circumferential ledge 219 on insidewall 218 of barrel 211 thereby preventing sheath from being pushed backinto the barrel, and exposing the needle.

The syringe 10 of the present invention may be a pre-filled syringe ormay be a syringe where fluid is drawn into barrel 11 by a user.

One particular variation contemplated by the present invention isdescribed with reference to FIG. 13, which variation is particularlyrelevant to a prefilled syringe 310. Sheath seal 350 comprises sealingmembers 358A, 358B and 358C and directly seals cannula end 400 to avoidcontact between boss 346 and fluid space 360. In this regard, boss 346is relatively shorter than elongate boss 346 previously described, tothereby allow aperture 355 of sheath seal 350 to directly seal ontocannula end 400 and thereby allow movement of sheath seal 350 alongcannula 341 until sheath seal 350 engages needle sheath 330 as plunger320 is depressed (shown progressively, left to right, in FIG. 13).

The invention also contemplates incorporation of a plunger disablingmeans 80 that may be applicable to any of the aforementioned embodimentsof syringe 10. An embodiment of a plunger disabling means 80 is shown inFIG. 14A where plunger end 14 of barrel 11 comprises opposed ledges 81A,81B, respectively having tapered surfaces 82A, 82B which allow travel ofbutton 22 of plunger 20 past ledges 81A, 81B toward needle end 13 ofbarrel 11 at the end of plunger 20 depression so that button 22 clipsunder ledges 81A, 81B, to thereby to impede, prevent or otherwise hindersubsequent withdrawal of plunger 20, as shown in FIG. 14B. This assistsin maintaining sheath 30 in its covering position over cannula 41 andprevents a user pushing sheath 30 back into barrel 11 in an attempt tore-use syringe 10.

Alternatively, the invention also contemplates incorporation of aplunger disabling means such as according to an embodiment described inInternational Application PCT/AU2005/000106, which is hereinincorporated by reference in its entirety.

In this particular embodiment, the plunger comprises two opposedratchets that are respectively alignable with the two pawls so as to becapable of engagement by the pawls and thereby impede, prevent orotherwise hinder withdrawal of the plunger during or followingdepression of the plunger. The barrel further comprises a collar havingan inner member and an outer member that are incapable of rotationrelative to each other. The outer member comprises the two pawls andfurther comprises two fingers that respectively slidably engage opposedguide slots on the plunger to thereby prevent or minimize rotation ofthe plunger relative to the collar. The inner member of the collar isoperable to prevent engagement of the plunger ratchet by the two pawlsuntil the plunger is depressed.

According to these embodiments, utilization of plunger disabling means80 allows plunger 20 to be immovably disabled at the end of depressionand fluid delivery thereby maintaining boss 52 of sheath seal 50 in aposition between legs 32A, 32B that prevents legs 32A, 32B of needlesheath 30 being “squeezed” together and needle sheath 30 removed fromneedle end 13 of barrel 11.

In light of the foregoing it will be appreciated that the presentinvention provides a needle sheath manually activated by plungerdepression or, optionally, a spring, which prevents, minimizes orreduces the risk of needlestick injury and/or syringe re-use.

A particular feature of the syringe needle sheath described herein isthat it is relatively simple in structure and does not require a guidingmember to assist guided movement of the sheath over the needle or topositively retain the sheath in its protection position over the needle.

A particular advantage of the spring activated syringe needle sheathdescribed herein is that the spring is pre-compressed, rather thangradually compressed during plunger depression, which provides a moreacceptable “feel” to the syringe user and hence improves the commercialattractiveness of the syringe.

Optionally, a further advantage is that a plunger disabling means may beincluded with the syringe of the invention to at least minimize theprobability of re-use.

Throughout the specification, the aim has been to describe the preferredembodiments of the invention without limiting the invention to any oneembodiment or specific collection of features. Various changes andmodifications may be made to the embodiments described and illustratedwithout departing from the present invention.

All patent literature referred to in this specification is incorporatedherein by reference in its entirety.

1. A syringe comprising a barrel and a needle sheath slidably locatedwithin the barrel, a plunger, a needle, a needle sheath and a sheathseal, arranged so that depression of said plunger urges said sheath sealto bear against said needle sheath and thereby move said needle sheathto cover or at least partly enclose the needle after delivery of fluidcontents of the syringe.
 2. The syringe of claim 1, further comprising aneedle mount to which is mounted said needle.
 3. The syringe of claim 1,further comprising a plunger seal which during plunger depression bearsagainst sheath seal thereby forcing said sheath seal to bear againstsaid needle sheath and move said needle sheath to cover or at leastpartly enclose the needle after delivery of fluid contents of thesyringe.
 4. The syringe of claim 1, further comprising a plungerdisabling means.
 5. The syringe of claim 1, which is a pre-filledsyringe.
 6. A syringe comprising a barrel, a needle and needle mountfitted to the barrel, a plunger, a needle sheath, an initiallycompressed spring and a sheath seal, arranged so that depression of saidplunger urges said sheath seal to bear against said needle sheath andthereby release said needle sheath from said needle mount to facilitatedecompression of said spring and thereby move said needle sheath tocover or at least partly enclose the needle after delivery of fluidcontents of the syringe.
 7. The syringe of claim 6, wherein said needlesheath co-operates with said needle mount to maintain said initiallycompress said spring.
 8. The syringe of claim 7, further comprising aplunger seal that engages said sheath seal.
 9. The syringe of claim 8,wherein during plunger depression, said sheath seal engages said needlesheath to thereby release said needle sheath from said needle mount andthereby allow decompression of said spring.
 10. The syringe of claim 9,wherein decompression of spring facilitates movement of said needlesheath to cover or at least partly enclose said needle after delivery offluid contents of the syringe.
 11. The syringe of claim 6, furthercomprising a plunger disabling means.
 12. The syringe of claim 6, whichis a pre-filled syringe.
 13. A syringe comprising a barrel and a needlesheath slidably located within the barrel, a plunger, a plungerdisabling means and a needle, said needle sheath operable to cover or atleast partly enclose the needle after delivery of fluid contents of thesyringe, wherein said plunger disabling means is operable to impede,prevent or otherwise hinder withdrawal of the plunger during orfollowing depression of the plunger.
 14. The syringe of claim 13,further comprising a sheath seal arranged so that depression of saidplunger urges said sheath seal to bear against said needle sheath andthereby move said needle sheath to cover or at least partly enclose theneedle after delivery of fluid contents of the syringe.
 15. The syringeof claim 14, further comprising an initially compressed spring and asheath seal, arranged so that depression of said plunger urges saidsheath seal to bear against said needle sheath and thereby release saidneedle sheath from said needle mount to facilitate decompression of saidspring and thereby move said needle sheath to cover or at least partlyenclose the needle after delivery of fluid contents of the syringe. 16.The syringe of claim 13, which is a pre-filled syringe.